Yanagisawa Formation

Yanagisawa Formation Tuzino et al., 2018

Invalid synonym: Upper Tomesaki Formation, Shimotomai Diatom-bearing Siltstone Member, Numanokubo Diatomite

Type locality: Yanagisawa creek, Sawada creek, Kintaichi, Ninohe city, Iwate prefecture
Coherent formation
middle Miocene (12 - 10.5 Ma)

Sedimentary facies: Marine
Sedimentary facies: Deep open sea
Climate: Warm temperate (Plants)
Lithofacies (Diatomite facies, Opal-A): Diatomaceous mudstone, Diatomite
Lithofacies (Porcelanite facies, Opal-CT): Shale
Lithofacies (Minor): Sandstone

Thickness (Diatomite facies): 30 m or thicker
Thickness (Porcelanite facies): 60 m
Upper limit: Conformity, partly unconformity (Shitazaki Formation), Unconformity (Kamimetoki Sandstone Member, Asanai Terrace Deposit)
Lower limit: Transitional (Zyumonzi Formation)

Yanagisawa Formation
[ Upper ]
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Kawaguchi Porcelanite Member
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[ Lower ]

Sannohe Group
[ Upper ]
~~~~~~~~~~~~~~
Kubo Formation
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Shitazaki Formation
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Yanagisawa Formation
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Zyumonzi Formation
~~~~~~~~~~~~~~
[ Lower ]

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

Distribution: Kintaichi - Kawaguchi, Ninohe city, Iwate pref.
Fossils: Fish scales, Diatoms (Coscinodiscus sp.), Radiolarians (Diartus petterssoni (=Cannartus petterssoni), Cyrtocapsella japonica, Eucyrtidium inflatum)
Fossils (Plantes): Cunninghamia protokonishii, Fagus paleocrenata, Fagus protojaponica, Machilus protothubnergi, Pasania cf. amygdalifolia, Pasania (Lithocarpus) miohypopheae, Quercus protoacuta

Tuzino et al. (2018) Geology of the Ichinohe District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 161p. (in Japanese with English abstract 4p.)